Process of preparing diazonium compounds from 4-aminodiarylamines



Patented Sept. 3, `1935 2in-P2180 PATENT orFicE `rnociiss oF PnEranrNc nrAZoNiUM CoM- PoUNns FaoM fi-AivnNonrAnrLAMINEs Wilhelm Koch,` Offenbach-lon-the-Main, Ger- Y many, assigner to General Aniiine Works, Inc., NewYork, N.-Y., a'corporaton of Delaware `No` Drawing. `Application March 5, 1934, Serial No. 714,205. In Germany March 7,"193 3 I 1 Claim. (Cl. 260--69) "QThe present invention relates to a process of preparing diazonium compounds from fi-aminodiarylamines;"more particularly it relates to `a process which comprises diazotizing a li-aminodiarylamine in a vreaction medium the pH-value of which is between 1 and 4.

In his publication entitled, The-DiazoCompounds of l-Aminodiphenylamine and Its Defi rivatives (inaugural dissertation, Leipzig, 1931),

Probst describes a series of complications which are liable tooccur in the diazotization'of-aminodiphenylamine and the derivatives thereof and which he proposes toavoid by a particular kind of diazotization. He states on page 15 of his publication that simultaneously withthe diazotizationanother process takesplace the nal result of which is Ythat part of the Ll-arninodiarylamine is split with formation of a para- Vquinone from the aryl radical carrying the amino-group and of a diazonium compound from thesecond aryl radical.

It Ahas been found experimentally that the extent of this cleavage or splitting `operation largely depends on the constitution Yof the base. Whereas, for instance, in the case of e-aminodiphenylamine itself, only about 3 to 5 percent. of the base are subjected to the cleavage when the `work is cautiously done, other bases of thisfseamine or Li21minodiphenylamines having substituents in 2.5-positions,` are split almost coinpletely during the` diazotization. r

` This invention is based on the observation that Vthe coursebffthe diazotization of the aminodiarylamines depends on the acidity of the reaction medium and that no cleavage by oxidation occurs if. the diazotization iscarried outl in a medium thepI-I-value of which is between l ande.

.i If the pI-I-yalue is considerablybelow 1, cleavage occurs, whereas if the hydrogen ion concentration is toosmall the diazotization no longer occurs.

` It has been found; that the cleavage does with certainty not occur at hydrogen ion concentrai tions which correspond to the 4pl-I-values between 1.5 and 4. i i As. reaction media there may be used aqueous solutions of salts, for instance, of zinc chloride,

copper chloride copper sulfate, ferrous sulfate used dilute acids or buffering solutions, or solu- 55 tions of mixtures of acids and salts of the desired pI-Ivalue. In all these cases a cleavage is entirely avoidedyduring the diazotization.

It is strongly advisable to' use the base in a state asnely divided as possible. For thispurpose the base may be ground, if desired, with the addition of a suitable'suspending or dispersing agent; or it maybe dissolved previously in a solvent miscible with water, Vsuch as Vacetone or alcohol, so that` if such a solution is mined with the aqueous reaction liquid the-baseis obtained in a iinely divided form.

The workingmethods may be varied within wide limits, as may be seen from the examples,

but the invention is not intended to be limited to the particular methods described therein. -By

diazotizing. the base, for instance, in a zinc chloride solution with sodiumA nitrite'or Zinc nitrite, the zinc chloride double salts of the diarylamino- Ll-diazcniumchlorides are directly obtained".

In the process of this invention there may, for instance, be used diphenylamines or-naphthylphenylamines or biphenyl-phenylamines and ani thracylphenylamines in which an amino group -portance for the production of ice colors of the 2.3-hydroxynaphthoic `acid arylaxnide seriesi The process of this `invention has a high technical value. It allows of producing the diazonium salts of the bases without secondary reactions in a pure form. Furthermore, itis only by employingthis invention that the technical utilization of a number ofjbases of this kind for dyestui u manufacturing purposes ble.

The following examples illustrate the invention. The parts are by weight unless otherwise stated:

has been made possi- Y (1) A solution of "76 parts of pure sodium ni-A trite in 500 parts of water `is introduced drop by drop `at about 3 0o C. in thecourse of about 3 hours into a suspension of 214 parts of very finely 'divided 4-'amino-3-methoxydiphenylamine in a solution `of 3000 parts of solid Zinc chloride in 3000 parts of Water.Vv When the diazotizaticn is complete the Whole is filtered. The part of the diazo salt which has already separated is extracted from the residue by treating it with Warm Water. The aqueous solution so obtained is cornbined with the ltrate and the diazonium zinc chloride double salt of the base is separated therefrom by addition of sodium chloride'.

In the same manner other bases, such as (4- amino-naphthyl-l) -4-ethoxyphenylamine, may

be transformed into the corresponding diazonium.

zinc chloride double salts without a cleavage occurring.

(2) A solution, having a temperature of about 40 C., of 242 parts of 4-amino-3-methyl-6- ethoxydiphenylamine in 1600 parts of denatured alcohol is quickly poured into a solution of about 30 C. of 3000 parts of solid zinc chloride and 76 parts of sodium nitrite in 3000 parts of Water. After a short time the diazotiization is complete and the product is Worked up as indicated in the preceding example.

In the same manner, other bases such as 4- amino-2,5-dimethoxydiphenylamine or 4-amino- 3-methyl-4'-methoxydiphenylamine or 4-aminophenyl- (ethoxynaphthyl) -amine may be transformed into the ycorresponding diazonium zinc chloride double salts.

(3) A solution of about 30 C. of 184 parts of 4-amino-diphenylamine in 1300 parts of acetone is quickly poured into a solution of about 30 C. of 3000 parts of solid zinc chloride in 3000 parts of water. The base remains dissolved. To this solution there is added drop to dropA at 25 C. to 30 C. inthe course of about 10 minutes a solution of 76 parts of pure sodium nitrite in 500 parts of Water. v

When the diazotization is complete the product is Worked up as indicated in Example 1.

(4) A solution of about 40 C. of 212 parts of 4-amino-2,5 dimethyldiphenylamine in 1500 parts of alcohol is quickly poured into asolutlon of about 30 C. of 3000 parts of solid zinc chloride and 76 parts of pure solid sodium nitrite in 3000 parts of Water. After a short time the diazotization is complete. 'I'he product is Worked up as indicated in Example 1.

By substituting in this example for the 4- amino-2,5dimethyldiphenylamine 268.5 parts of 4-amino-3-chlorophenyl- (naphthyl-Z') -amine and diazotizing in the manner described, there is obtained the diazonium-zinc chloride double salt of 4-amino-3-chlorophenyl- (naphthyl-2) am ine.

For the purpose of dissolving the bases there may be used other neutral organic solvents miscible with Water, such as methanol, isopropyl alcohol or the like. l

- (5) A solution of about 40 C. of 184 parts of 4-amino-diphenylamine in 1300 parts of alcohol is quickly poured into a solution of about 30 C. of 350 parts of copper chloride hydrate'and 76 parts of pure solid sodium nitrite in 5000 parts of Water. After a short time the diazotization is complete. After filtration any diazo salt which may have already been separated is extracted from the residue by treating it with Warm Water. The aqueous solution so obtained is combined With the filtrate and the diazonium salt is sep arated therefrom by adding a solution of '72 parts of solid zinc chloride in '72 parts of Water and salting out with sodium chloride. For. the purpose of dissolving the base there maybe used other neutral organic solvents miscible With Water, such as acetone, isopropyl alcohol, or the like. Y-

In the same manner other bases, such as 4-amino2,5-dimethyldiphenylamine or 4-aminophenyl-1( [6ethoxynaphthy12] amine) may be transformed into their diazonium compounds Without cleavage occurring.

(6) A solution of about 40 C. of 214 parts of 4-amino-B-rnethoxydiphenylamine in 1500 parts of acetone is quickly poured into a solution of about 30 C. of 2800 parts of ferrous sulfate (FeSOrHHzO) and 76 parts of pure solid sodium nitrite in 7000 parts of Water. After a short time the diazotization is complete and the product is Worked up as indicated in Example 5.

Instead of ferrous sulfate there may also be used solutions of, for instance, 360 parts of copper chloride hydrate in 5000 parts of Water or of 3300 parts of copper sulfate hydrate in 5000 parts of water or of 530 parts of aluminium sulfate of the formula Alz(SO4)3.l2I-I2O in 6000 parts of Water, or the like.

('7) A solution of 76 parts of pure sodium nitrite in 500 parts of Water is rather rapidly introduced drop by drop at about 30 C. into a suspension of 268.5 parts of very finely divided 4-amino- 3-chlorophenylnaphthyl-2'-amine in a solution of 250 parts of glacial acetic acid in 5000 parts of water. When the diazotization is complete the whole is ltered. The part of the diazo salt which has already separated is extracted from the residue by a treatment with Warm water. The aqueous solution so obtained is combined with the filtrate and the diazonium zinc chloride double salt is separated therefrom in the usual manner with the aid of zinc chloride and sodium chloride.

(8) 110 parts of glycocoll and 85.8 parts of sodium chloride are dissolved together in Water and the solution is diluted to about 20000 parts by volume. There is run into this solution a dilute hydrochloric acid which contains 80.3 parts of HC1 and which has been obtained by diluting, for instance, 250.16 parts of hydrochloric acid of 20 B. of 32.1 per cent. by Weight with about 10000 parts by volume of Water. The Well mixed solution containing glycocoll, sodium chloride and hydrochloric acid is then adjusted with water to exactly 36666 parts by volume. The pH-value of the hydrochloric acid contained in it is now 1.5. The solution is heated to about 30 C. and 76 parts of pure solid sodium nitrite are introduced into it. After a short stirring a fine suspension of about 40 C. of 214 parts of 4-amino-3-methoxydiphenylamine in 1500 parts of Water is quickly added. After a short time the diazotization is complete. The resultant diazonium salt may be precipitated in the usual manner.

(9) An aqueous solution of 210 parts of pure crystallized citric acid, made up to exactly 10000 parts by volume, is well mixed with an aqueous solution of 286.8 parts of pure crystallized disodium phosphate, made up to exactly 4000 parts by volurne. The solution thus obtained has an acidity of a pH value of 3.4. 76 parts of pure solid sodium nitrite are added and a solution of about 40 C. of 272 parts of 4amino-2,5diethoxydiphenylamine in 1900 parts of alcohol is rapidly run in. VThe whole is subsequently stirred for a short time whereupon the diazotization of 4- amino2,5diethoxydiphenylamine is complete. After addition of the necessary quantity of a suitable mineral acid the corresponding diazonium salt may be separated in a solid form in known manner.

(10) 541.4 parts of caustic soda solution of 32.5 per cent. by Weight (38 B.) are slowly run into a solution of 462 parts of pure crystallized citric acid in about 20000 parts by volume of Water. The solution of the resultant sodium citrate is then Well mixed with a dilute hydrochloric acid containing 80.3 parts of HC1 and obtained as det scribedrin Example 8. The mixture is made up with Water to exactly 44000 parts by volume. The solution so obtained has an acidity of the pH- value=3.5. It is mixed With 76 parts of pure solid 10 sodium nitrite and there is rapidly run into the 

